JPS63101085A - Diffused joining method - Google Patents

Abstract

PURPOSE:To facilitate joining of materials and to reduce its cost by cleaning or activating the material surface of one hand by etching, etc., and then, bringing material to be joined of the other hand into close contact with said material to pressurize the materials in a vacuum or a gas atmosphere where the cleaned and activated state can be maintained. CONSTITUTION:A processing chamber 1 and a pressurization treatment chamber 13 to join the materials are provided respectively and a gate valve 20 is arranged between these chambers. After the materials to be joined, namely, a piezoelectric body plate 9 and a glass plate 17 are subjected to the ultrasonic cleaning, the plate 9 and the glass plate 17 are sucked and fixed on a lower electrode 3 of the processing chamber 1 and on the lower part of a hydraulic cylinder 14 of the pressurization treatment chamber 13 respectively. The plasma etching is performed on the plate 9 between an upper electrode 2 and the lower electrode 3 and then, the plate 9 and the glass plate 17 are superposed and brought into close contact with each other to pressurize and join these by the prescribed pressure in the pressurization treatment chamber 13. Since the material can be joined under the relatively low degree of vacuum, pressurizing force and temperature, the joining of the materials is facilitated and its cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a diffusion bonding method that allows materials to be bonded together at a much lower temperature than conventional bonding temperatures.

[Prior art and its problems]

Conventional methods for joining similar or dissimilar materials can be roughly classified as follows.

(Bath welding method in which 11 materials are heated to high temperature and melted to join them.

(2) A diffusion bonding method in which materials are heated in a vacuum or gas atmosphere to a temperature below their melting point and then joined by applying pressure.

(3) A method of joining using solder metal.

(4) Method using organic adhesive.

All of the methods (11 to (3)) above require heating of the joining materials, so in general, ■Materials with different thermal expansion characteristics will generate greater thermal stress during joining, and will be less likely to join. It is easy to cause cracks in the material or deterioration of its properties.

■Materials whose properties change are sensitive to heat 9 For example, s-type materials,
Acefumas material. Piezoelectric materials and the like lose their original properties due to heating during the bonding process, and complex reprocessing is required to reproduce them.

It has problems such as:

Further, the problems of the above method will be described in detail as follows.

With method (1), it is difficult to join materials with large differences in fj melting points. Furthermore, it is generally not applicable to non-metallic materials such as ceramic and phosphor.

Method 12) has the advantage that it is possible to obtain a strong bond even with dissimilar materials by appropriately selecting the conditions without melting the materials at a lower temperature than method (1). Motsu. However, since it is generally necessary to heat the material in a vacuum or under a gas-filled atmosphere, if the material contains elements with high vapor or atmospheric pressure, the evaporation of the elements may cause changes in the material composition or deterioration of the properties. There is a problem that the inside of the container is easily contaminated due to evaporation. In addition,(
Method 2) requires a fairly large load during bonding, and has the disadvantage that it is difficult to apply to mechanically fragile materials such as piezoelectric ceramics and resin.

Method (3) allows joining at a lower temperature than methods +11 and +21 by selecting the type of solder or brazing material. However, there are restrictions in that it is difficult to apply to materials that have poor wettability with solder and brazing filler metals, such as ceramics and organic materials.

(The organic adhesive No. 41 can be bonded at around 100'C or below, or at room temperature depending on the type of adhesive.
Thermal expansion of the materials to be joined 4? It is characterized by the fact that the difference in housing is hardly a problem. On the other hand, the mechanical strength of the joint, especially high temperature strength and chemical resistance, is inferior to those obtained by methods (11 to 31) described above.

Recently, joining of amorphous alloys and fine ceramics (for structural and functional use), which have been attracting attention as new materials, and furthermore, with the progress in the field of microelectronics, dissimilar materials with significantly different thermal expansion characteristics 1. For example, glass - for functional use. It has also become necessary to bond ceramics (for example, piezoelectric ceramics, adhesives, etc.), ceramics (for structural use) to metals, metals to functional ceramics, adhesives, and the like. However, it is difficult to achieve these goals using the conventional bonding methods outlined above. For this reason, there is a need for the development of a method and apparatus that can join materials at low temperatures and with high precision while minimizing deformation or strain on the materials.

From the above point of view, bonding under ultra-high vacuum has been proposed as a method that enables low-temperature bonding of materials.
Normally, atoms on the surface of solid materials have bonds that are unnecessary for interatomic bonds, but in the atmosphere, they combine with oxygen like rust or with various pollutants and lose their activity. The principle of bonding under ultra-high vacuum is to remove excess contaminants such as oxygen bonded to the surface of the materials using ultra-high vacuum glue 11-Jung action, and to activate the bond, which connects the bonds between the materials. This method has the advantage of being able to easily join materials that are susceptible to heat and stress, or dissimilar materials with significantly different thermal expansion characteristics. However, in this joining method, 10 to 10 t is required to keep the material surface clean.
A vacuum atmosphere of less than orr is required, and in order to bond without pressure, the surface of the material is required to have extremely high flatness and smoothness, and to be in close contact over the entire surface of the bonding material. Although a vacuum level of 10 to 10 torr is achievable with small laboratory equipment, it is difficult to achieve even with current technology in industrial scale equipment.Therefore, this ultra-high vacuum bonding method is It is hoped that a method and apparatus will be developed that will enable bonding in a simpler manner while taking advantage of these advantages. An object of the present invention is to provide a diffusion bonding method that enables precision bonding of materials having different thermal expansion characteristics.

[Key points of the invention]

According to the present invention, the above purpose is to perform etching and ion irradiation on the surface of one of the materials to be joined.

After cleaning or activating it using one of the methods such as sputtering or vapor deposition, the other bonding material is superimposed on the cleaned or activated surface in an X-empty or gas atmosphere while maintaining that state. , it can be achieved by applying pressure load.

The present inventors believe that if contaminants attached to the surface of a material are removed by some method, and while maintaining that state, another material is superimposed on the surface of this material and a pressurized load is applied to it, an extremely high The idea was that the extremely high degree of vacuum required by vacuum bonding methods would not be necessary, and the high heating temperatures required by conventional methods would also be unnecessary. Furthermore, we conducted various studies from the viewpoint of 0 or more, estimating that this method would make it easier and more economical to manufacture the welding equipment. Plasma etching and ion implantation are methods for removing, cleaning, or activating.

Coating with an activated metal by sprue, glue, or vapor deposition is optimal, and after this treatment, the other material that is to be bonded quickly is superimposed while maintaining this state (preventing contaminants from adhering). If you pressurize it, it will be 10 to 10
It has been found that bonding can be carried out at a vacuum level of 10 to 10 torr, or in a reduction or inert gas atmosphere such as H2eAr. In the case of the present invention, the lower the degree of vacuum, the more preferable it is. A good bond could be obtained within the range of 0. This includes plasma etching, etching, ion implantation, submersion, and rinsing.

If the stress during bonding is reduced to 0, which is thought to be due to the material surface being sufficiently cleaned or activated by vapor deposition, etc., the adhesion of the bonding surfaces will improve, and this will be effective in increasing the bonding force. However, in the case of the present invention, good results were obtained with a pressing force in the range of 0.1 to IQQ%; and according to the method of the present invention, bonding was possible even at room temperature. In addition,
Heating during bonding activates the diffusion of atoms at the bonding surface and improves the bonding performance, but it requires a heating means to be installed in the bonding device, making the device larger and more complex. There are several types of bonding methods, so the temperature or temperature to be heated can be selected depending on the bonding material and the purpose of bonding.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail, using a piezoelectric plate and borosilicate glass as materials, and plasma etching as a method for cleaning the material surface.

FIG. 1 shows an outline of the apparatus used in the present invention. In FIG. 1, 1 is an upper electrode 2. A lower electrode 3 equipped with a matching circuit 4 and a high frequency power source 5. Vacuum exhaust valve6. Gas supply valve7.
and a side wall 8. A piezoelectric plate 9 as a bonding sample is set on the lower electrode 3. Furthermore, the processing chamber 1 is equipped with a pusher rod 10 and a moving stage 1 for moving the bonded sample. An O-ring 12 is placed between the pusher rod 10 and the wall 8, and plays a sliding role. I am accomplishing it.

On the other hand, 13 in FIG. 1 is a pressure treatment chamber, and the pressure treatment chamber 13 has a hydraulic cylinder 14. Frame 15. Vacuum exhaust valve 1
6 is arranged, and the glass plate 17, which is the other bonded sample, is placed under the vacuum suction pulp 1 at the bottom of the hydraulic cylinder 14.
It is adsorbed by 8. Further, 19 is an OII ring, which has the role of maintaining the hydraulic cylinder 11 and preventing airtightness when the cylinder 14 is raised and lowered.

In the bonding apparatus shown in FIG. 1, a gate valve section is disposed between the processing chamber 1 and the pressurized processing chamber 13, and has a structure that can be opened and closed as necessary. Reference numeral 21 is an O11 ring, and its role is the same as that of 19 above.◎In this bonding apparatus, after the piezoelectric plate 9 and the glass plate 17 are ultrasonically cleaned in acetone, the piezoelectric plate 9 is placed in the processing chamber 1. Set on the lower electrode 3, the glass plate 17 is suctioned and fixed to the lower part of the hydraulic cylinder 14 by a vacuum suction pulp 18. after that.

The processing chamber 1 and the pressurized processing chamber 13 are each made into independent processing chambers using the gate valve 2), and the vacuum exhaust valves 6 and 16 are opened to evacuate the chamber to a vacuum of 10 torr.◎10
When a vacuum of torr is reached, only the vacuum exhaust valve 6 that evacuates the processing chamber 1 is closed, and the gas supply valve 7 is opened to introduce argon gas from the outside until the gas is filled into the chamber. Thereafter, a voltage is applied to the upper and lower electrodes 2 and 3, and plasma etching is performed on the surface of the piezoelectric plate 9 for ~ω minutes. When the plasma etching process for a predetermined time is completed, the voltage application is removed and vacuum evacuation is performed. The valve 6 is closed again to evacuate the processing chamber 1 and evacuate it to IQ torr. After the processing chamber 1 reaches a vacuum of 10'' torr, the gate valve 19 is raised.

By pushing the piezoelectric plate 9 with the pusher rod 10, it is moved along the moving stage 11 to the top of the pedestal 14 of the pressure treatment 913, and placed directly below the hydraulic cylinder 14. Thereafter, the hydraulic cylinder 11 was lowered, the glass plate 17 was superimposed on the surface of the piezoelectric plate 9, and the two were joined at room temperature by further pressurizing to a predetermined pressure. After cutting in the width direction with a dicing saw and polishing, the bonded cross section was observed with a 100x optical microscope. It was confirmed that there were no defects such as holes in the bonded part, and the properties were good.@With conventional technology, it was impossible to bond the piezoelectric plate and the glass plate at room temperature. , it is possible according to the method of the present invention! It was proven.

In addition, even if the positions of the piezoelectric plate and the glass plate were reversed in the method 2 of the present invention described above, and the surface of the glass plate was plasma etched and then bonded, the same good bonding as described above could be obtained. .

The above explanation uses a piezoelectric plate and a glass plate, and uses plasma etching as a means of cleaning and activation. However, other material combinations and methods such as ion implantation, sputtering, and vapor deposition may also be used. Furthermore, it was experimentally confirmed that good bonding could be obtained even with reducing gas or inert gas in the pressurized treatment plan 4II.

〔Effect of the invention〕

As explained above, the present invention cleans or activates the surface of one of the materials to be joined by any one of etching, ion irradiation, sputtering, vapor deposition, etc., and then cleans or activates the surface of one of the materials to be joined while maintaining that state. This is a method in which another bonding sample is placed on the surface of the material and placed in contact with it by applying pressure.Compared to conventional bonding methods, bonding can be performed at a much lower temperature (1, for example, around room temperature) and at an extremely low pressure. As a result, it is possible to precisely join dissimilar materials with significantly different thermal expansion properties, even brittle materials with extremely low mechanical strength, and even materials whose properties are sensitive to heat.
It has the effect that bonding is possible without deteriorating its characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a bonding apparatus for carrying out the bonding method of the present invention.

Claims (1)

[Claims] 1) After cleaning or activating the surface of one of the materials to be joined by one of etching, ion irradiation, sputtering, vapor deposition, etc., the joining material is cleaned or activated in a vacuum or gas atmosphere that can maintain that state. A diffusion bonding method characterized by bonding by bringing another bonding material into close contact with the surface and applying pressure.